2H2 + O2 → 2H2O
The chemist is standing inside a room with oxygen in the air and has a balloon filled with hydrogen. The chemist holds a small flame up to the hydrogen balloon. When the balloon pops, the hydrogen explodes in a ball of fire.
explain which part of the reaction is higher in energy
The higher energy part of the reaction is the formation of the H-H bonds in the hydrogen molecule (2H2). Breaking these bonds requires an input of energy, while forming them releases energy. When the chemist ignites the balloon, the heat of the flame provides the energy needed to break the H-H bonds in the hydrogen molecules. Once the hydrogen molecules are broken apart, the hydrogen atoms can react with oxygen (O2) to form water (H2O), releasing a large amount of energy in the form of heat and light.
In the given reaction, 2H2 + O2 → 2H2O, the combustion of hydrogen (H2) with oxygen (O2) forms water (H2O). The reaction releases energy in the form of an explosion.
To determine which part of the reaction is higher in energy, we need to consider the bond energies of the bonds involved. Bond energy is the amount of energy required to break a bond between two atoms. Generally, breaking bonds requires an input of energy, and the formation of bonds releases energy.
In the given reaction, we have to break the bonds in hydrogen molecules (H2) and oxygen molecules (O2) and form the bonds in water molecules (H2O). Let's examine the bond energies involved:
1. Breaking the bonds in hydrogen gas (H2):
- The bond in a hydrogen molecule (H-H) has an average bond energy of 435 kilojoules per mole (kJ/mol).
2. Breaking the bonds in oxygen gas (O2):
- The bond in an oxygen molecule (O=O) has an average bond energy of 498 kJ/mol.
3. Forming the bonds in water (H2O):
- The bonds in a water molecule (H-O-H) have an average bond energy of 463 kJ/mol.
From these values, we can see that the bond energy for the oxygen-oxygen (O=O) bond is higher than the bond energy for the hydrogen-hydrogen (H-H) bond. Therefore, breaking the oxygen-oxygen bonds in the oxygen gas (O2) requires more energy compared to breaking the hydrogen-hydrogen bonds in the hydrogen gas (H2).
This indicates that the oxygen gas (O2) is higher in energy compared to the hydrogen gas (H2) in the given reaction. When the hydrogen balloon is ignited, the released energy is sufficient to break the oxygen-oxygen bonds in the oxygen gas, leading to an explosive reaction and the production of water.
In the given chemical equation, 2H2 + O2 → 2H2O, the result is the formation of water (H2O) from the reaction between hydrogen (H2) and oxygen (O2) gases.
In this reaction, the combustion of hydrogen takes place. Hydrogen gas is highly flammable and easily combustible due to its low activation energy. The reaction between hydrogen gas and oxygen gas releases a large amount of energy, which is evident from the explosion and the subsequent ball of fire observed when the flame is brought close to the hydrogen-filled balloon.
The higher energy part of this reaction is the combustion of hydrogen (2H2) to form water (2H2O). This combustion reaction is exothermic, meaning it releases energy in the form of heat and light. The energy released during the reaction is what causes the balloon to explode and the fireball to form.